The invention relates to a display tube comprising an envelope consisting of a neck, a cone and a faceplate including flat or slightly curved, substantially rectangular display window and a skirt which is substantially parallel to the axis of the envelope. The skirt and the display window meet at a sharply curved transition portion of the faceplate. The display window has on its inside a substantially rectangular display screen, and the tube includes means in the neck to generate at least one electron beam.
The invention also relates to a picture display device comprising such a display tube.
Such a display tube may be a colour display tube. In that case the display screen usually comprises a pattern of triplets of luminescent stripes or dots of a luminescent material luminescing in three different colours. However, it is also possible for the display tube to be a display tube for displaying monochromatic pictures, such as a tube for displaying letters, digits, characters and figures, a so-called D.G.D.-tube (Data Graphic Display).
Recently developed display tubes have flatter display windows, as is described in the Journal of Electronic Engineering, August 1982, p. 24. The colour display tube described has a substantially rectangular display window in which, however, the outer contour of the skirt and display window is slightly barrel-shaped. Such a slightly barrel-shaped outer contour is assumed to be necessary to meet the stringent safety requirements protecting against implosion of the tube. For tubes which are placed in a cabinet and the outer contour of which is concealed from the viewer by a bezel, the barrel-shaped contour need not be a disadvantage because the inner edge of the benzel can adjoin the edge of the rectangular display screen. However, for tubes the display window of which slightly projects outside the cabinet (so-called "push-through" mounting) and hence the benzel cannot be used, the substantially rectangular display screen on the inner wall of the much less rectangular faceplate expose to dark areas above and below and on the left and on the right of the displayed picture, which areas vary in width and are annoying to the viewer.